What Is an IFC File? The Open Standard for BIM Collaboration Explained

What Is IFC? / What Is an IFC File?

IFC stands for Industry Foundation Classes. It is an open, vendor-neutral file format developed and maintained by buildingSMART International for exchanging BIM data between different software applications.

In the world of Open BIM, IFC is the common language that allows every tool at the project table to communicate without a proprietary interpreter in the middle.

Think of IFC as the PDF of BIM. When you export your building model as an IFC file, you are capturing a complete snapshot of that model at a specific point in time.

The snapshot includes the full geometry of every element, plus all the metadata attached to it: material properties, fire ratings, spatial relationships, cost data, and more.

Anyone with an IFC-compatible viewer or software can open that file and see exactly what you intended them to see. What they cannot do is edit the model and push changes back to your authoring tool. That is by design. An IFC file is built for sharing and coordination, not for live collaborative editing.

The standard IFC file extension is .ifc, which follows the STEP (Standard for the Exchange of Product model data) format. You may also encounter related formats: .ifcXML encodes the same data in XML syntax, and .ifcZIP is a compressed version for sharing large files over limited bandwidth. The .ifc format is what the vast majority of project teams use day to day.

Industry Foundation Classes Explained

The IFC standard was born in 1994, initiated by Autodesk alongside a consortium of 12 US companies, including HOK Architects and Honeywell, with the goal of enabling integrated application development across the AEC industry.

From the start, the vision was to create a shared data language that software vendors could adopt without needing to build one-to-one translators between every possible pair of tools.

The standard is now maintained by buildingSMART International, a global NGO with member chapters across Europe, Asia, and the Americas.

History of IFC

The journey from that 1994 founding to today's ISO-published standard spans three decades of incremental improvement and broad industry adoption. The first official IFC release came in 1997.

Subsequent versions refined the schema, expanded the object library, and responded to the growing complexity of BIM project delivery.

IFC 2x3, released in 2007, became the most widely deployed version in the industry and remains the compatibility baseline for many legacy workflows.

IFC 4 followed in 2013, introducing significant architectural improvements. IFC 4.3, ratified as ISO 16739-1:2024, is the current active version and represents the most complete and capable version of the standard to date.

What "classes" means

The "classes" in Industry Foundation Classes refers to the object classification system. IFC organizes every building element into a standardized object class. For example: a wall is not just a flat surface in a 3D model; it is an IfcWall object that carries a defined set of geometric properties, attribute data, and relationships to adjacent elements.

The same logic applies to IfcDoor, IfcColumn, IfcBeam, IfcStair, and hundreds of other classes. Because every platform that supports IFC uses the same class definitions, a door in Revit is recognized as a door when it arrives in ArchiCAD or Navisworks. No translation required.

Published as ISO Standard

IFC is not just a de facto industry convention. It is an official international standard published as ISO 16739-1:2024. This gives it the same regulatory standing as other construction and engineering standards, which is why you see it referenced in government procurement requirements and BIM mandates around the world.

IFC and Open BIM: How They Work Together

Open BIM is both a philosophy and a practice focused on collaboration. It means using open, non-proprietary standards so different software tools can work together seamlessly.

On purpose, it rejects vendor lock-in workflows, where a project team is forced to use a single software ecosystem because their data formats are incompatible with anything else.

So, Open BIM means you can choose the best tool for each discipline without sacrificing the ability to coordinate models across the project.

IFC as an OpenBIM Enabler

IFC is the primary technical standard that makes Open BIM possible at the file level. When your team adopts IFC as the exchange format for model sharing, you can export a Revit model and have it read accurately by ArchiCAD, Tekla, Navisworks, Solibri, or any other IFC-certified platform.

This is done without manual data re-entry, without rebuilding elements in a new tool, and without losing the metadata that makes BIM valuable in the first place.

BuildingSMART Certification

However, not all IFC implementations are equal. Software vendors must pass buildingSMART's IFC certification process to prove that their IFC import and export is reliable and schema-compliant.

When you are evaluating tools for your team's BIM workflow, buildingSMART certification is a useful quality signal. Certified software has been tested against the standard and is less likely to produce broken or incomplete IFC files that cause coordination issues.

Why IFC Is the Standard for BIM Collaboration

Here are the top reasons that make IFC the standard for BIM collaboration:

Vendor Neutrality

One of IFC's most important characteristics is that no single software company owns or controls it. The standard is governed by buildingSMART International, an independent nonprofit. This means that a major software vendor cannot unilaterally change the standard to advantage their own products. IFC belongs to the industry, and every software vendor operates on equal footing when implementing it.

Government Mandates

IFC adoption is mandatory in a growing number of markets. Norway, Denmark and Finland all have public sector requirements for IFC-compatible BIM delivery on government-funded construction projects.

In the UK, the BIM Level 2 mandate, which applies to centrally procured public projects, requires IFC-compatible deliverables. If your firm works on public sector projects in these markets, IFC compliance is a contractual necessity, not just a best practice.

Data Preservation

Think about your project files in 10–30 years. Proprietary formats like .rvt or .pln depend on the software that created them. If that software changes, is discontinued, or becomes unavailable, access to your data can be lost.

IFC, as an open ISO standard, avoids this risk. Future IFC-compatible tools will still be able to open today's files.

For asset owners, facility managers, and public clients, this long-term accessibility makes IFC a strong choice for project handover and data preservation.

How IFC Works in BIM Workflows

Let's break down how IFC works in BIM workflows:

Export Process

The process starts in your authoring tool. When you are ready to share your model with another discipline or stakeholder, you export it as an IFC file using your software's built-in IFC export function.

During the export, you configure the settings to specify which elements to include, what property sets to carry over, which IFC version to target, and what Level of Development (LOD) is appropriate for the intended recipient.

Getting your export settings right is important. A poorly configured export can produce an IFC file that is missing critical data or that includes so much irrelevant information that it becomes unwieldy to work with.

Import & Federation

The recipient imports the IFC file into their software. If they are using Navisworks for clash detection, they import your architectural IFC alongside the structural and MEP models to create a federated model for coordination.

If they are using Solibri for model checking, they load the IFC to run automated rule checks against it.

In both cases, the geometry and metadata from your original model are preserved through the IFC exchange, giving the recipient an accurate, data-rich representation of your design intent.

COBie Handover

IFC files are often used alongside COBie (Construction Operations Building Information Exchange) at the end of a project. COBie is a structured data format for asset information: equipment lists, maintenance schedules, warranty data and the information facility managers need to operate a building.

When you deliver an IFC file at project completion, often paired with a COBie spreadsheet, you are giving the building owner a structured, software-agnostic record of what was built and how to maintain it.

Practical Limitation

There is one critical characteristic of IFC you need to keep in mind: an IFC export is a snapshot, not a live link.

When you update your Revit model and re-export an IFC file, that new file does not automatically appear in your coordination model or your colleague's Navisworks session.

Your team needs to manage IFC exchange on a coordinated schedule, with clear protocols for who exports, when and how updated files are distributed. Document this in your BIM Execution Plan and stick to it.

IFC Versions and Specifications

IFC has evolved through a series of major versions since the standard's first public release. Here are the key versions:

IFC 1.0 appeared in 1997. This was the original public release of the standard. IFC 2x3, released in 2007, became the most widely supported version in the industry and remains the safe fallback for projects where maximum software compatibility is needed.

IFC 4, introduced in 2013, brought a significant architectural overhaul: improved geometry representations, better property set handling, and enhanced support for MEP and structural elements.

IFC 4.3, now published as ISO 16739-1:2024, is the current recommended version and adds dedicated schema support for infrastructure elements including bridges, roads, railways, and ports.

IFC 5 is in development and represents a more fundamental refactoring of the standard than any previous update. It is being designed to support advanced automation use cases, improved machine-readability, and integration with emerging technologies including USD (Universal Scene Description) and digital twin platforms.

Compatibility Guidance

Before exporting any IFC file on a new project, confirm which IFC version every team member's software supports. Then apply the following:

• Use IFC 2x3 if any team member is on older software, or if version compatibility is uncertain. It offers the broadest support across the industry.
• Use IFC 4 when all team members are running current software versions. It is the recommended standard for modern projects.
• Document the agreed version in your BIM Execution Plan to avoid compatibility issues mid-project.

IFC File Formats and Structure

IFC-SPF (.ifc)

This is the most common IFC format. It is identified by the .ifc extension. It is a plain text STEP Physical File where every object in the building model is represented as a line of text.

Because it is plain text, an IFC-SPF file is both compact and human-readable to someone familiar with the schema. It is universally supported across all IFC-compatible software and should be your default format for standard project exchanges.

IFC-XML (.ifcXML)

The format encodes the same building model data in XML syntax. This makes it useful for integration with XML-based enterprise systems, web services and data pipelines.

The trade-off is file size: an IFC-XML file representing the same model as an IFC-SPF file will typically be several times larger. Unless you have a specific technical reason to use IFC-XML, such as feeding data into a web-based asset management platform, stick to .ifc for routine model exchanges.

IFC-ZIP (.ifcZIP)

It's a ZIP-compressed package containing either an IFC-SPF or IFC-XML file. For large, complex building models, IFC files can grow to hundreds of megabytes. IFC-ZIP compression can reduce file size substantially, making it practical to share models over email, common data environments, or project platforms with file size limits.

Most BIM tools can import IFC-ZIP files directly without requiring you to manually decompress them first.

How to Open and View IFC Files

Free IFC Viewers

You do not need a paid BIM authoring tool to view an IFC file. Free IFC viewers give anyone on your project, including clients, contractors and facilities teams, the ability to inspect a model without a software license.

• BIMvision: A widely used free viewer with strong IFC support across versions.
• Solibri Anywhere: The free tier of Solibri's platform; allows full model viewing without a license.
• xBIM Xplorer: An open-source viewer that handles large IFC files well.
• Autodesk Viewer: Browser-based and requires no software installation; accessible to anyone with a link.

In BIM Authoring Tools

If you are working in a BIM authoring environment, you can import IFC files directly into most major platforms. Revit, ArchiCAD, Navisworks, Tekla, and virtually all current BIM tools include IFC import functionality.

This allows you to view and reference coordination models from other disciplines in your native workflow without requiring those disciplines to share proprietary format files.

Online Viewers

For project stakeholders who do not have BIM software and do not want to install a viewer application, browser-based IFC viewers provide a zero-installation option.

Platforms such as openifcviewer.com allow anyone to drag and drop an IFC file and view it directly in a web browser. This is particularly useful for clients, contractors, and facility managers who need to inspect a model at handover without accessing specialized BIM tools.

How to Convert IFC Files

IFC conversion is not a clean, lossless process. Here is a look at what each conversion path preserves and what it loses to help save you time and prevent coordination errors:

IFC to DWG/DXF

If someone on your project team needs IFC data in a DWG or DXF format for use in AutoCAD, most BIM tools support exporting an imported IFC as DWG. Dedicated geometry conversion tools such as Allplan and FME also handle IFC-to-DWG conversion and give you more control over how the geometry is translated.

Be aware that converting from IFC to DWG will strip the object intelligence and metadata from the IFC, leaving you with geometry-only output. This is fine for reference geometry, but the output cannot be used as a working BIM model.

IFC to Revit

Revit can import IFC files natively, but IFC-to-Revit conversion is not a clean round-trip. Some elements may import with reduced fidelity and manual cleanup is often needed to assign correct Revit categories, families and parameters to imported elements.

Autodesk's IFC for Revit plugin, available as a free add-in, improves the import fidelity significantly compared to Revit's built-in IFC import.

If you are working on a project where IFC models need to be taken back into Revit for editing, you must budget time for post-import cleanup.

IFC to PDF and image

When you need to produce a PDF or image output from an IFC model, the simplest approach is to open the IFC file in a free viewer and capture screenshots or rendered views.

For more controlled technical output, open the IFC in Navisworks or Solibri and use their built-in export functions to produce rendered images or 2D sheet PDFs. This is useful for producing visual deliverables for clients or contractors who need a static record of the model at a specific stage.

IFC vs DWG: What's the Difference?

If you have ever been asked to explain why your project uses IFC rather than just sharing DWG files, the answer comes down to data richness, purpose, and workflow context.

DWG is Geometry-Only: A DWG file stores 2D or 3D geometry as lines, arcs, and surfaces. It contains minimal embedded data and no object intelligence. A door in a DWG file is a collection of lines and arcs, not a door object with material properties, fire ratings, and spatial relationships.

DWG is excellent for what it was designed for: 2D drafting and AutoCAD-based drawing production.

IFC is Data-Rich: An IFC file stores geometry and a complete object data model. Every element carries its type classification, material properties, fire rating, thermal performance data, cost information, spatial relationships to adjacent elements and whatever other properties your team has configured in the authoring tool.

That data richness is what makes IFC valuable for coordination, compliance checking, quantity takeoffs, and facility management handover.

When to Use IFC vs DWG

Use DWG for 2D drafting workflows and for sharing geometry with teams that use AutoCAD as their primary tool. Use IFC for cross-software BIM collaboration, for government-mandated BIM compliance delivery, and for structured data handover to facility managers and asset owners at project completion.

In many projects, you will use both: IFC for BIM coordination and DWG for 2D drawing packages.

Pros and Cons of IFC

Pros

• Vendor-Neutral and Free to Use: IFC is an open standard with no licensing fees. Any software vendor can implement it, and any user can export, share and open IFC files without paying royalties or requiring a specific software subscription.
• Supports Full BIM Data: Unlike geometry-only formats, IFC carries the full BIM data model: element classification, material properties, spatial hierarchy, cost data, performance attributes and everything else your authoring tool has populated.
• Government-backed ISO standard: IFC's status as ISO 16739-1:2024 gives it regulatory credibility and ensures it is taken seriously in public procurement and compliance contexts.
• Enables Open BIM and multi-software collaboration: IFC is the technical foundation for true Open BIM workflows, allowing any IFC-certified software to participate in a coordinated project regardless of vendor.
• Long-term data preservation: As an open standard, IFC files created today will be accessible by future IFC-compatible software, protecting your investment in BIM data across the full building lifecycle.

Cons

• IFC exports are snapshots: An IFC file does not maintain a live link to the source model. Every update requires a new export and re-distribution, which demands disciplined model exchange protocols from your team.
• Import fidelity varies by software: The quality of IFC import in different platforms is not uniform. Some tools handle IFC imports cleanly. Others lose data, misclassify elements, or require significant post-import cleanup.
• File sizes can be large: Complex building models can produce very large IFC files. Without compression or careful export configuration, IFC files can become unwieldy to share and process.
• Not all IFC elements map cleanly between platforms: The IFC schema is comprehensive, but software implementations vary. Elements that export cleanly from one tool may not import with full fidelity in another, especially across major version differences.
• Geometry cleaning sometimes required post-import: Particularly when converting IFC to a format like Revit or ArchiCAD, imported geometry may require manual cleanup to function correctly within the target software's parametric environment.

How to Start Using IFC in Your BIM Projects

Now that you are ready to move from understanding IFC to actually using it on a live project, here is a practical starting framework:

Step 1: Check Software IFC Certification

Before committing to an IFC-based workflow, verify that every team member's software has been certified by buildingSMART. The certification directory is available at buildingsmart.org and lists software that has been independently tested for IFC compliance.

Uncertified software may produce incomplete or unreliable IFC exports that create coordination problems downstream.

Step 2: Agree on IFC Version

At project kickoff, align your entire team on a single IFC version to use for all model exchanges. For new projects where all team members are using current software, IFC 4 is the recommended standard.

If some team members are on older software with limited IFC 4 support, IFC 2x3 is the safe fallback for maximum compatibility. Document the agreed version in your BIM Execution Plan.

Step 3: Set Export Settings

IFC export quality depends heavily on how your export is configured. Work through the IFC export settings in your authoring tool to specify which element types to include, which property sets to export and which Level of Development is appropriate for the intended recipient.

Before your first project exchange, test the export with a sample model and have the recipient confirm that the import reads correctly in their software.

Step 4: Establish a Model Exchange Schedule

Because IFC files are snapshots rather than live links, your team needs a structured exchange protocol. Define how frequently IFC files are exchanged between disciplines, who is responsible for issuing updated files, where files are deposited (typically your Common Data Environment), and how version control is managed.

Put this in your BIM Execution Plan and enforce it consistently throughout the project.

How PiAxis Enhances IFC-Based BIM Workflows

IFC coordination solves the cross-software model exchange problem. But once coordination is complete and approved, you face a different bottleneck: producing detailed 2D construction documents.

This is the phase where manual drafting time peaks, where teams rebuild details from scratch that have been drawn and refined on previous projects, and where the productivity gains from your IFC coordination workflow can be lost.

PiAxis addresses this bottleneck directly: Detail retrieval from coordinated projects, PiAxis indexes construction details from your firm's past BIM projects, including those delivered using IFC-based coordination workflows.

When your team reaches the documentation phase on a new project, PiAxis makes those past details instantly searchable and retrievable. Instead of drafting a wall section or connection detail from scratch, you can pull a proven detail from a previous project, adapt it for the current context, and move on. The time savings compound across every detail package on every project.

Maintaining Firm Standards Across Platforms: Multi-platform BIM environments are the reality for most mid-to-large AEC firms. Your architects may work in Revit, your structural engineers use Tekla, and your MEP consultants use OpenBIM tools.

As details and standards are developed across those environments over years of project delivery, PiAxis ensures that the detail library your firm has built, regardless of which authoring tool produced the original drawings, is preserved, organized, and reusable. The value your team has created in past projects does not disappear because a new project uses a different software platform.